Spray coating apparatus



Oct 5; 1940. D. s. BIRMINGHAM 2,217,724

I SPRAY commie APPARATUS 2 Sheets-Sheet 1 Filed July 20, 1938 VEUUF,

DONALD G. BIRMINGHAM Oct. 15, 1940.

D. G. BIRMINGHAM SPRAY COATING APR-ARATUS lfiled Juli 20, 1958 STORAGE TANK 2 Sheets-Sheet 2 4 PREssuRE 42 SUPPLY 54 TANK HEATER DONALD G. BIRWNGHAM Patented Oct. 15, 1940 UNITED STATES SPRAY COATING APPARATUS Donald G. Birmingham, Aberdeen, Wash.,'assignor to Harbor Plywood Corporation, Hoquiam,- Wash., acorporation of Delaware Application July 20, 1938, Serial No. 220,221

10 Claims.

This invention relates to apparatus for spray coating sheet material.

More specifically this invention relates to apparatus for coating both broad faces .of veneer sheets with an adhesive.

In themanufacture of laminated material such as, for example, plywood, the constituent laminations are united together by means of an adhesive.

I It is customary to apply the adhesive only to the core sheet or lamination and for this reason both broad faces of the core sheet must be coated.

The present invention now provides a spray coating apparatus accommodating sheet material such as wood veneer to coat both broad faces thereof with a uniform film of adhesive. According to this invention the sheets are fed through the coating apparatus in an upright or vertical position. It has been found that a passage of veneer sheets in a horizontal position through a spray coating apparatus results in the formation of ponds or pools of adhesive on the top faces of the sheets while the bottom faces retain a relatively less amount of adhesive thereon. For the production of uniform plywood panels, however, 25 it is essential that both broad faces of the core sheets be uniformly coated.

It is, then, an object of this invention to provide a spray coating apparatus for sheet material.

A further object of this invention is to provide a machine for uniformly coating both broad faces of sheet or board material with a liquid.

A further object of the invention is to provide a spray coater for plywoodcore sheets.

Another object of this invention is to provide a glue coating apparatus for plywood core sheets wherein the glue or adhesive is continuously circulated through the apparatus under uniform pressure.

Other and further objects'of the invention will become apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings which disclose a preferred embodiment of the invention.

On the drawings:

Figure 1 is a top plan view, with parts shown in horizontal cross section, of a spray coating apparatus according to this invention.

Figure 2 is a side elevational view of the apparatus shown in Figure 1.

Figure 3 is a fragmentary cross-sectional view,

with parts in elevation, taken along the line III-HI in Figure 2.

A spray housing I 8 straddles the longitudinal 1O beams l4 and I5 and issupported thereon midway between the transverse beams l3. A second spray housing I9 likewise straddles the longitudinal beams l6 and IT. The housing I9 is aligned with the housing l8.

The housings l8 and [9 are closed at the top' with covers (Figures 2 and 4) and have sloping bottoms 2| communicating with vertical ducts 22. Both ducts 22 are joined through a Y-duct 23 with a stack or vent 24. This stack 24 discharges uncondensed vapors from the spray housings l8 and I9.

The bottoms of the ducts 22 receive pipes 25 therein for draining adhesive collected therein. v The pipes 25, as shown in Figure 4, discharge into top of the storage tank 29. Thus, adhesive in the storage tank is recirculated from the bottom to the top of the tank by the pump 3|. However, the three-way valve also receives a pipe 34 therein communicating with a pressure tank 35. This pressure tank 35' receives a supply of adhesive from the storage tank 28 and maintains this supply under a constant pressure supplied to the tank 35 by a pump 36. The pump 35communicates with the top of the tank 35 through a pipe line 31- having a pressure regulator 38 therein interposed between the tank and the pump 36. A blow-oil valve 39 is provided at the top of the tank to relieve pressure therein when adhesive is being pumped into the tank.

A float 40 is mounted on the end of an arm 4| in the tank 35. The arm 4| extends through a side of the tank in pivotal relation thereto and 55 l with a heat exchanger 46 supplied with steam rear faces thereof.

is connected through links 42 and 43 to the core of the valve 32.

When the tank 35 has a. predetermined supply of adhesive therein, the float 48, floating on top of the adhesive in the tank, holds the valve 32 in the position shown in Figure 4. In this position the pump 3| merely recirculates the adhesive from the bottom of the storage tank 29 to the top of the tank and thus maintains the adhesive in a constantly mixed, uniform condition. However, when the supply in the tank 35 drops below a predetermined level, the float 46 will have moved downwardly to openthe valve 32. with the pipe line 34. The pump 3| will then supply adhesive .from the tank 28 to the tank 35, until the float 40 again closes the valve 32.

A pipe line 45 joins the bottom of the tank 35 or other heating fluid through an inlet pipe 41 and an outlet pipe 48. The adhesive is heated to a desired temperature in the heater 46 as it flows therethrough.

The heated adhesive is circulated out of the heat exchanger 46 into a pipe 49 having branch pipes 58, 52 and 53 joined therewith.

The branch pipes 58 to 53 inclusive each have three horizontal pipes 54, 55 and 56 extending through an adjacent side wall of a spray housing l8 or l9 as is best shown in Figure 4. The pipes 54 to 56 inclusive each have a spray head 51 threaded on the end thereof.

The pipes 54 to 56 are in spaced superimposed relation with the center pipes 55 ofiset horizontally from the pipes 54 and 56 as is best shown in Figures 1 and 2. Pairs of spray heads 51 are thus diametrically opposed to each other in each spray housing l8 and I9.

The spray housings l8 and I9 have vertical inlet and outlet openings 68 through the front and Guide boards or flaps 6| and 62 are adjustably mounted adjacent each opening 68 along the sides thereof. These flaps 6| and 62 can be moved to vary the size of the openings 68 for accommodating veneers of different thicknesses. The flaps 6| and 62 mounted on the inlet opening 68 extend into the housing as shown in Figure 1. The flaps 6| and 62 mounted adjacent the outlet opening 68, however, extend out of the housing as shown in Figure l.

Veneer sheets such as V are fed through the housings l8 and I9 between the spray heads 51 to receive a coating'of adhesive thereon.

The device of this invention includes feedin mechanism for passing veneer sheets V through the spray housings.

The feeding mechanism will now be described.

The longitudinal ,beams I4 and I5 as well as the beams l6 and I1 have U-shaped straps or bands 65 and 66 mounted in spaced relation on the inlet sides of the housings l8 and I9. Similar bands 61 and 68 are mounted on the beams at the discharge sides of the spray housings as is best shown in Figures 1 and 2.

The bands 65 and 61 have stub-axles 18 mounted thereacross slightly above the longitudinal beams. The bands 66 and 68 each have long axles 1| extending therebetween and across the space between the bands as shown in Figure 1. Thus one axle 1| serves both bands 66 while another axle 1| serves both bands 68.

Sprocket gears 12 aremounted on each axle and 1| adjacent the inside of each leg of the bands 65, 66, 61 and 68 respectively. The sprocket gears 12 mounted between the legs of bands 65 and 66 each have a chain 13 trained therearound. Pairs of chains 13 are connected by means of cross rods or bars 14 as best shown in Figure 1. p

Likewise the sprocket gears 12 mounted between the legs of the bands 61 and 68 have chains trained therearound with pairs of chains 15 joined by transverse bars or rods 16.

The axles 1| receive sprocket gears 80 on the ends thereof in spaced relation from the bands as shown in Figure 1. A chain 8| is trained between the gears 88. An axle 1| is driven by means of a chain connection 82 as shown in Figure 1, so that a rotation of the first axle 1| on the discharge end of the assembly rotates the axle 1| on the intake end of the assembly to move all of the rods or transverse bars 14 and 16 in timed uniform relation. These bars support the bottom edges of the vertical veneer sheets V.

The veneer sheets V areheld in vertical position by two sets of opposed vertical rods 85 carried on sprocket chains 86 that are trained between sprocket gears 81 and 88 mounted horizontally near the tops and bottoms of the bands 65 to 68 inclusive on vertical shafts or axles 89 rotatably carried by the bands. The vertical axles 89, as shown in Figure 3, are driven through bevel gears 90 and 9| from the horizontal axles 1|.

Thus the vertical rods 85 are driven with the horizontal rods 14 and 16 to engage the broad faces of the veneer sheets V and move thesame in a vertical position.

As best shown in Figure 1 the veneer sheets V are moved into the spray housings I8 and I9 between the flaps 6| and 62. The portions of the veneer sheets in the housings l8 and I9 are unsupported but each sheet projects through the discharge openings of the housings and is supported on the rods 16 before it has moved off the rods 14.

As shown in Figure 2, a platform 92 may be mounted at the inlet side of the apparatus to permit operators to easily feed veneer sheets on top of the racks 14 and between the vertical rods 88.

From the above description it should be understood that this invention provides an apparatus for spray-coating sheet material such as wood veneers, board or the like. The apparatus ineludes conveyors for passing the sheet material through spray housings in a vertical position. The apparatus also includes a circulating system for the spray coating material whereby the same is kept in a constantly mixed uniform condition and may be supplied to the articles to be coated in a heated condition. y

I am aware that many changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art.

I claim as my invention: 1. A spray coating apparatus comprising a closed housing having elongated slots in opposite sides thereof, flaps adjustably secured along the edges of said slots for regulating the size of the openings defined by the slots, spray devices in u tal beams, a housing straddling said beams at the 7 elongated slots in opposite side thereof, U-shaped bands secured in spaced relation on said beams on each side of said housing, horizontal axles rotatably mounted between the legs of said bands, sprocket gears mounted on said axles adjacent the inner face of each band leg, endless conveyors trained around said sprocket gears, vertical axles rotatably mounted in each band between the legs thereof, sprocket gears secured on said vertical axles, vertical conveyors trained around said sprocket gears and means for driving said horizontal and vertical axles in unison to move the conveyor for feeding sheet material in vertical position through the slots of said housing.

3. A spray coating apparatus comprising in combination a frame having-a pair of transverse beams and four longitudinal beams in spaced parallel relation, spray housings straddling adjoining longitudinal beams at the mid-points thereof, horizontal conveyors mounted on said longitudinal beams on each side of said housing, vertical conveyors mounted above said horizontal conveyors and means for driving all of said conveyors in unison for feeding sheet material in vertical position through said housing.-

4. A spray coating apparatus comprising a pair of housings each having vertically elongated slots through opposite sides thereof for receiving sheet material in vertical position therethrough, ducts communicating with the bottom of each housing, a Y-duct joining said first mentioned ducts a ventilating stack communicating with the Y-duct, a horizontal. conveyor and a pair of opposed vertical conveyors adjacent the sides of each housing, means for driving all of said conveyors in unison to feedsheet material through the vertical slots of the housing and spray devices in said housing for coating the sheet material as it passes therethrough.

5. A spray coating apparatus including a spray housing, means for draining liquid from said housing, a storage tank for receiving the drained liquid, a pump for pumping liquid out of said storage tank, a pressure supply tank, a. return pipe line to said storage tank, a three-way valve for controlling flow of liquid from said pump to said pressure supply tank or to said return pipe line, a float device in said pressure supply tank for operating said valve, means for maintaining a-constant pressure in said pressure supply tank, a heater for receiving liquid from said pressure supply tank, and spray devices in said housing receiving heated liquid from the heater whereby a substantially constant supply of liquid under pressureis maintained and a constant circulation of liquid from the storage tank is obtained to .supply thoroughly mixed liquids under controlled constant pressure to the spray devices.

6. A spray coating apparatus comprising a 5 housing having front, rear and side walls, a top wall and a sloping bottom, said front and rear walls having'verticall'y elongated slots therein, adjustable flaps secured along the edges of the slots for regulating the effective size thereof, a duct communicating with the sloping bottom. means ventilating said ductand a drain pipe at the bottom of said duct.

7. A spray coating apparatus comprising a vertical housing having vertically. elongated in-fls let and outlet openings on opposite sides thereof,

a plurality of spray heads in said housing on opposite sides of said openings, and mechanical conveyors positioned wholly outside said housing for moving sheet material through said housing in vertical position.

8. A coating device comprising a closed housing having aligned vertically elongated slots in opposite walls thereof, means positioned wholly without said housing for feeding sheet material through said slots and spray devices in said housing facing the .broad surfaces of the sheet material.

9. A device for coating sheet material comprising a closed'housing shorter than said sheet material and having vertically elongated slots in opposite walls thereof, means at each side of the housing positioned wholly without said housing for feeding said sheet material through said slots, said means terminating immediately adjacent the slots to support projecting positions of the sheet material and spray devices in said housing facing a broad surface of the sheet material.'-

'10. A coating device for sheet material com- 40 prising two aligned endless conveyors having horizontal upper runs spaced apart for a distance less than the length of the sheet material,

a pair of endless vertical conveyors above the upper run of each of said horizontal conveyors, said vertical conveyors having their inner runs in spaced opposedrelation to receive therebetween sheet material supported on the upper runs of said horizontal conveyors, said inner runs of the vertical conveyors being sufliciently close to each other to hold the sheet material in upright position, means for driving all of said conveyors in unison, and spray devices positioned intermediate said spaced horizontal conveyors for coating said sheet material.

\ DONALD G. BIRMINGHAM. 

